TULANE COBRE: PHOSPHORYLATION IN SOLID MUSCLE TUMOR ALVEOLAR RHABDOMYOSARCOMA

腺泡状横纹肌肉瘤（ARMS）是儿童最常见的软组织肉瘤之一，其特征是t（2;13）（q35;q14）染色体易位，导致两种对肌肉发育重要的转录因子Pax 3和FKHR融合。目前，很少有人知道的潜在的分子机制，调节Pax 3和致癌融合蛋白Pax 3-FKHR的活动，以及如何这种调节可能是重要的ARMS的发展。因此，本提案的总体目标是了解磷酸化如何调节Pax 3的转录活性以及Pax 3-FKHR如何改变这种调节。这一目标将通过两个具体目标来实现：（1）研究磷酸化在Pax 3和Pax 3-FKHR调节中的作用。这一特定目标将通过鉴定Pax 3上的磷酸化位点来解决， Pax 3-FKHR，确定磷酸化如何影响每种蛋白质的分子生物学活性（即-DNA结合、蛋白质稳定性和转录活性），确定磷酸化如何改变Pax 3和Pax 3-FKHR依赖性增强的原代成肌细胞增殖和分化，并分析磷酸化对Pax 3-FKHR致癌活性的重要性。(2)鉴定负责磷酸化Pax 3和Pax 3-FKHR的激酶。这一具体目标将“。通过使用标准色谱技术从原代成肌细胞中分离磷酸化Pax 3和Pax 3-FKHR的激酶，证实这些激酶负责体内磷酸化，并使用激酶抑制剂来确定这些激酶的抑制如何影响先前描述的Pax 3和Pax 3-FKHR依赖性生物学效应（即-增殖增强、凋亡增强和致癌活性）。比较Pax 3和Pax 3-FKHR通过磷酸化调节的差异将为了解Pax 3-FKHR在ARMS形成中的作用提供重要见解。

The solid muscle tumor Alveolar Rhabdomyosarcoma (ARMS), one of the most frequent soft tissue sarcomas in children, is characterized by the t(2;13)(q35;q14) chromosomal translocation, which results in the fusion of two transcription factors important for muscle development, Pax3 and FKHR. At present, little is known about the underlying molecular mechanisms regulating the activities of Pax3 and the oncogenic fusion protein Pax3-FKHR and how this regulation may be important for the development of ARMS. Therefore, the overall objective of this proposal is to understand how phosphorylation regulates the transcriptional activity of Pax3 and how Pax3-FKHR may alter this regulation. This objective will be addressed through two specific aims: (1) To investigate the role of phosphorylation in the regulation of Pax3 and Pax3-FKHR. This specific aim will be addressed by identifying the sites of phosphorylation on Pax3 and Pax3-FKHR, determining how phosphorylation affects the molecular biological activities of each protein (i.e. - DNA-binding, protein stability, and transcriptional activity), determining how phosphorylation alters the Pax3- and Pax3-FKHR-dependent enhanced proliferation and differentiation of primary myoblasts, and analyzing the importance of phosphorylation on the oncogenic activity of Pax3-FKHR. (2) To identify the kinases responsible for phosphorylating Pax3 and Pax3-FKHR. This specific aim wil'. be addressed by using standard chromatographic techniques to isolate the kinases that phosphorylate Pax3 and Pax3-FKHR from primary myoblasts, confirming that these kinases are responsible for the phosphorylation in vivo, and utilizing kinase inhibitors to determine how inhibition of these kinases effects the previously described Pax3 and Pax3-FKHR-dependent biological effects (i.e. - enhanced proliferation, enhanced apoptosis, and oncogenic activity). The comparison of the differences in the regulation of Pax3 and Pax3-FKHR by phosphorylation will provide important insights into the role of Pax3-FKHR in the formation of ARMS.